Proximate composition, total phenolics and total flavonoids level, DPPH radical scavenging activity, and cytotoxicity were determined in the methanol extracts of different plant parts of Youngia sonchifolia at reproductive growth stage. Crude protein and crude fat were present as the highest amount in flowers, and crude fiber in the stems and roots. The highest content of phenolics [mg ferulic acid equivalents (FAE) kg-1dry weight (DW)] was found in flowers (highest) and followed by leaves, stems and roots (lowest). Flavonoids [mg rutin equivalents kg-1 DW] level, however, showed the highest in leaf extracts and lowest in root extracts. The antioxidant potential of the methanol extracts from the plants dose-dependently increased DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging activity (%). DPPH radical scavenging activity were highest in root extracts (IC50 = 1,135.6 mg kg-1) and followed by leaf, stem and flower extracts. By way of MTT (3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyl tetrazolium bromide) assay, methanol extracts of roots showed the highest anticancer activity on human cancer cell line Calu-6 for human pulmonary carcinoma (IC50= 196.3 mg kg-1) and HCT-116 for human colon carcinoma (IC50=623.6 mg kg-1)